scope:

Scope and Assumptions

The following characteristics identify the scope of this document:

♦ It includes QoS metrics that are intended to support the Linear/Broadcast IPTV service defined in ATIS-0800002 [1], and not any other ATIS IIF defined IPTV services. However, it is recognized that many QoS metrics may also be applicable for other ATIS IIF defined IPTV services, such as Video On Demand (VOD), where many similarities exist.

♦ The QoS metrics apply to applicable measurement points, along an end-to-end path from the Video Head End (VHE) Egress to the IPTV Terminal Function (ITF) - AKA, Set Top Box (STB). Although not all information may be accessible (for example, due to encryption), the best possible view is provided where applicable and accepted by ATIS IIF.

♦ Many performance objectives will be architecture-dependent and therefore defining values/objectives for these QoS metrics may not be useful. There is a class or classes of QoS metrics that are independent of network architectures (i.e., service) and it may be appropriate to define values/objectives for these metrics. However, this is subject for further study and out of scope for this document.

♦ The current focus does not include an exhaustive analysis of associated service flows (e.g., DRM control/signaling) and considers this generally for further study, exceptions permitting - e.g., channel change by means of Internet Group Management Protocol (IGMP) joins and leaves.

♦ At this moment, the consumer domain is considered mainly from a fixed wireline home environment perspective and no specific consideration is given to Wireless Local Area Network (WLAN) and mobile environments. Analysis of such environments and the impact of the currently selected set of QoS metrics are for further study.

♦ At this time, ATIS IIF only considers video, audio, and the synchronization between audio and video in scope. Synchronization of subtitles with the Audio-Visual (AV) stream, closed captioning, emergency alerts, and other data/information types related to audio/video are for further study.

♦ At this time, ATIS IIF considers availability, usability and correctness of the Interactive Program Guide (IPG) out of scope and concentrates only on the responsiveness. Note that this document does not include Linear/Broadcast IPTV with trick modes.

♦ Measurement methodologies are for further study.

ATIS IIF recognizes that the IPTV VHE and Video Hub and Serving Offices (VHO, VSO) may require specific QoS metrics that could be different than the currently defined set of metric definitions. At this time, ATIS IIF recommends use of ETSI TR 101.290 [8] Motion Pictures Expert Group (MPEG) metrics and will consider the study of QoS metrics for this environment for further study.

It is assumed that the ITF at startup, before it reaches the service availability mode, will be involved in a variety of setup/control communications with any IPTV oriented network/service attachment functions in the Service Provider (SP)/Network Provider (NP) networks. At this time, ATIS IIF did not analyze the traffic in the control plane associated with this action to form any opinion on the need for QoS metrics, and considers this to be for further study.

ATIS IIF does not assume that only Real Time Protocol (RTP) is used, and allows MPEG Transport Stream (TS) directly over User Datagram Protocol (UDP) configurations. It is understood that when RTP is not used, this complicates accurate calculation of several metrics including dropped packets. Additional information/alternatives to calculate such metrics without RTP is for further study. In general, Transmission Quality metrics refer to IP packets.